The present invention relates to a device for static fixation of the jaw relation, or relative position, in intraoral registration by means of a registration instrument set composed of a pin holder with a vertically adjustable stylus (support pin) for placement in a jaw, for instance the upper jaw, and a writing or recording plate with an alignment clamp (fixation plate) mounted thereon for placement in another jaw, for example the lower jaw. To make a dental prosthesis, the dentist must take jaw impressions, and these must be determined in their position both with respect to the jaw joint and in the relation to one another. To determine the relation between the joint and the jaw (axial relation), known techniques, employing headgear which are not the subject of this invention, are available.
Accordingly, the spatial relationship between the upper and lower jaws (jaw relation) must then be defined. To this end, it is for instance known, as disclosed in German Published, Non-Examined Patent Application DE-OS 28 25 470, to use a recording instrument set whose essential function is to produce a recording, based on certain specified patterns of motion between the upper and lower jaws of the patient, from which recording the proper jaw relation can be ascertained. A recording plate, i.e. a "jaw bite plate", is placed in the lower jaw and acts as a kind of blackboard for the support pin or stylus fixed in the upper jaw via a pin holder. This support pin arrangement is then capable of recording the jaw positions of interest for prescribed relative motions between the upper and lower jaws, and the result is typically an arrowlike structure, i.e. "symphysis track angle", on the basis of which the jaw relation can be determined.
To adjust the support pin on the recording plate, a displaceable clamp, or fixation plate, is provided, which has a recess for temporarily holding the tip of the support pin, that in turn is disposed in a predetermined relation with the afore-mentioned arrowhead-like marking.
Once the jaw relation has been ascertained from these measurements, this position is fixed, or keyed, for instance by introducing a hardenable material, i.e. impression plaster, between the recording plate and the pin holder by means of a syringe. This process is very uncomfortable for the patient, and very time-consuming for the dentist, as well as being expensive in terms of material. Moreover, for the duration of hardening of the impression material, it is no longer assured that the bite position will be maintained, nor can it continue to be monitored.